Electrical Impedance Tomography In Human Abdomen Utilizing Ultrasonic Reflection Information

Structure and functional imaging of biological tissues are of great significance for clinical monitoring as well as early diagnosis and treatment of disease.Electrical Impedance Tomography(EIT)is a distribution reconstructing and visualization measuring method based on the sensitive mechanism of electromagnetic field.Based on the different electrical characteristics under different physiological and pathological conditions,EIT could be adopted to provide visualization measurement of biological tissues.EIT has shown potential application prospects in clinical medicine.For the problem of imaging and detecting lesions in human abdomen with multi-organizational distributions,major contributions are as follows:(1)Based on the summaries and analysis of the development of biomedical imaging methods and electrical impedance tomography,the two-dimensional EIT simulation model was established according to anatomical structure to detect lesions in abdomen.The influencing mechanism of EIT in abdomen tissues was discussed.(2)The impact of noise on lesion detection was discussed with the lesion conductivity variation and lesion size being the detecting indicators.Based on the analysis of influencing mechanism of liver lesion conductivity and size on boundary voltage,the smallest variation of lesion conductivity and size that can be detected using EIT with a certain measurement noise were obtained.(3)A novel abdomen domain discretization method was proposed through analyzing the lesion resolution of EIT inside abdomen domain.This method was based on the sensitivity distribution and the abdomen domain was discretized into polygon meshes with different size.Compared with the uniform square meshes,image reconstruction based on the polygon meshes provides better distinguishability for liver lesion.(4)For the structure variation problem among different organisms,the shape of liver was redrawn using liver boundary positioning information acquired from ultrasonic reflection signal.Image reconstruction was based on the new reference model and imaging error caused by the inaccurate reference structurewas overcome.Liver lesion boundary positioning information acquired from ultrasonic reflection signal was adopted to optimized the selection of regularization coefficient.Results showed that lesion boundary was more distinguishable and the imaging artifacts were overcome.Experiments with gel model was conducted.Both simulations and experiments prove the effectiveness of the EIT method in human abdomen lesion detection utilizing ultrasound reflection information.